The effects of spacing and genetic factors on growth and tree form quality traits of plantation-grown jack pine
Notice bibliographique
Résumé
Overall tree form ofjack pine (Pinus banksiana Lamb.) growing in natural stands \nvaries from straight slender trees with compact crowns to broad, limby and even multi-stemed \ntrees. Jack pine grown in plantations at conventional spacings of 2 m develops \nform traits undesirable for forestry utilization. The goal of this study was to investigate \nthe effects and interaction of spacing and genetic factors on plantation-grown jack pine to \ndetermine the potential benefit of a selection program based on form traits. Ten wind-pollinated \nfamilies were collected from each of six natural fire-origin stands from east \nand west of Lake Nipigon in northwestern Ontario that had been subjectively rated as \ngood, average and poor in form. These sixty families making up six form-quality groups, \ntogether with an additional twenty plus tree families making up two more form-quality \ngroups, were established at two planting sites with contrasting soil texture and fertility at \nspacings of 1, 2 and 3 m. Eight tree form quality traits?branch length, branch diameter, \nbranch angle, branch number, relative branch diameter, relative crown width, number of \ncrooks, and taper were measured and analyzed together with two growth traits?height \nand diameter at breast height (DBH) at age eight. General linear models were used to \nevaluate the effects of site, spacing, form-quality group, family and the relevant \ninteractions on all traits except number of crooks which was not normally distributed. All \njack pine growth and form traits except branch number were greatly affected by spacing. \nMost of the change in form traits occurred when spacing increased from 1 to 2 m with \nlesser change from 2 to 3 m. This effect was more pronounced at the more fertile test site. \nForm-quality groups were significantly different for only two of the form traits?branch \nlength and branch angle with this effect again being more evident at the fertile test site. \nHowever, the family effect was significant for all seven tested form traits as well as the \ntwo growth traits suggesting that any of these traits would readily respond to family \nselection. A definite provenance effect was demonstrated for growth traits and stem \ntaper; the western sources grew faster with more favourable taper. None of the form quality \ngroup X spacing nor the family x spacing interactions were significant. \nHeritabilities and genetic correlations were determined for all traits separately for each \nspacing at each test site. Traits height, branch angle and taper had the highest \nheritabilities, with individual heritabilities of greater than 0.15, and the traits branch \ndiameter, relative branch diameter and relative crown width had values less than 0.05. \nThe two growth traits together with growth-related form traits tended to be strongly \npositively correlated with the exception of height and relative crown width. However, \nbranch angle and branch number showed no strong correlations with any other tree form \nand growth traits. Both heritabilities and genetic correlations were more meaningful for \nthe more fertile test site due to larger components of family variance.
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Comment cette classification a été obtenuedéplier
Prédiction machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule source (Gemma direct ou Codex distillé), pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».